This should solve your request:
.container {
display: inline-block;
background: aliceblue;
min-width: 210px;
min-height: 85px;
position: relative;
}
.maxim {
position: absolute;
width: 100%;
max-width: 100%;
background-color: lime;
}
<div class="container">
<header>
<strong>12345620</strong>
<span>description</span>
</header>
<span class="maxim">
Lorem ipsum Lorem ipsum Lorem ipsum Lorem ipsum oposum
</span>
</div>
<div class="container">
<header>
<strong>1234567890</strong>
<span>description and more text is here also possible</span>
</header>
<span class="maxim">
Lorem ipsum Lorem ipsum Lorem ipsum Lorem ipsum oposum
</span>
</div>
2
solved Second div no wider than first div